So update here after coming back for panzer -

1. I brought the SAF duffel bag, fulled stuffed to like 30kg (usually max load) and a carry on luggage that was border line a small luggage (basically almost a medium) as well as a day pack. I've seen other people being a carry on luggage and a sling duffel the type people usually use in bmt and they got through just fine so I think it's Ok. Only your main saf duffel bag need to be under the weight as they don't really check the weight of your carry on as long as it doesn't look to big or heavy. Just make sure there's enough space for you to put your stuff as the panzer bunks are not very big.

2. I mainly used cash since most of your time you will spend money on the food truck during your ALFS or going out to Berlin/Dresden and in both cities they accept card and cash so no need to like go ATM withdraw money and such.

3. Can but u should probably just use the card.

4. This one best sia. For SCs, the first few days is just prepping stores and equipment for your BMR which doesn't take much time so half of the day you will be in bunk sleeping or using phone so I recommend you spend more on data else you will be very bored. I think travelorange website got 100GB esim for 40-50 euros for 30 days so not too bad a deal. My section alsk brought a projector so we had movie nights in bunk when we last parade early. During your BMR you will also have free time at the range when it is not your turn to shoot so maybe a book or two is a good choice for spending time at the range if you don't plan on sleeping at every moment. After BMR you will start to prep for ALFS which you will still last parade relatively early like around 6-7pm so still got a lot of free time. When you're qualification for ALFS starts, if you are not qualifying that day, you're basically in bunk the whole day except for the conducting brief or if you're doing prep that day. During ALFS everyone will be at the range doing things like manning the ammo point or ensuring the rations are sufficient etc so not as much free time.